101666051550509 has 4 divisors (see below), whose sum is σ = 101754226791516. Its totient is φ = 101577876309504.

The previous prime is 101666051550487. The next prime is 101666051550517. The reversal of 101666051550509 is 905055150666101.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 75314800128100 + 26351251422409 = 8678410^2 + 5133347^2 .

It is a cyclic number.

It is not a de Polignac number, because 101666051550509 - 2¹² = 101666051546413 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (101666051550599) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44087618774 + ... + 44087621079.

It is an arithmetic number, because the mean of its divisors is an integer number (25438556697879).

Almost surely, 2^{101666051550509} is an apocalyptic number.

It is an amenable number.

101666051550509 is a deficient number, since it is larger than the sum of its proper divisors (88175241007).

101666051550509 is an equidigital number, since it uses as much as digits as its factorization.

101666051550509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88175241006.

The product of its (nonzero) digits is 1215000, while the sum is 50.

The spelling of 101666051550509 in words is "one hundred one trillion, six hundred sixty-six billion, fifty-one million, five hundred fifty thousand, five hundred nine".